"Mind you, I asked him why he wasn't playing soccer if he was going to wear shinpads, so the first scrum he obviously wasn't too happy and gave me a black eye. We took four tightheads off them which rarked them up even more, and my face got a good working over and was pissing out blood. I just sucked it up [because] that's one thing about playing front row, taking the game back to its roots, although that's really taking it back to its roots!"
Harris is the only Bay of Plenty player in the juniors for the world champs being played at Danie Craven Stadium in Stellenbosch, although there's a blue and gold tinge to the team with former Rotorua Boys' High midfielder Marnus Hanley, now studying in Hamilton, also selected.
Mt Maunganui's Nick Ross, who played most of his rugby out of Hamilton Boys' High, is also in at lock. Ross, studying media and communications at Canterbury University, is the son of former Bay of Plenty player Craig Ross, who played in New Zealand Colts teams in 1975 and'76 and for Natal in the Currie Cup.
Incredibly, Harris is in just his third year playing in the front row after reinventing himself while at Tauranga Boys' College, having played all his rugby at No 8. The arrival from Reporoa of Sam Cane and Carl Axtens prompted the rethink, with Harris' days of playing off the back of the scrum numbered with the New Zealand secondary schools players in the mix.
Selected at rake for the Bay of Plenty and Chiefs under-18 teams, the technical aspects of his new position took a while to get to grips with.
"My first year of rep footie at hooker was testing. My body type hasn't changed because I'm still growing into the weights and the bulking up, but the core roles of scrummaging and throwing have really taken some work.
"My throwing's still a bit on and off but I'm getting more consistent."
Harris went to his first national under-20 camp in November. Being one of four hookers vying for two spots fired his resolve to leave nothing to chance.
He and Tauranga Sports' Jeff Thwaites trained all through summer but Harris was left to do the hard yards alone when Thwaites broke his leg in the first trial game.
"Making it was a huge focus and I didn't want to let myself down by not being fit enough - no-one wants to be that dude walking around the field or being unable to make that final sprint to catch a pass."
He gave himself a few days off over Christmas and treated training like a fulltime job.
"I kept trucking all through summer, although it was hard after Jeff got injured. But if I was going to make it it needed to be me pushing because no-one else would do the work for me.
"Some people don't like getting out of bed early to hit the gym and I was one of those but, when you boil it down rugby is like a job and if you don't do your job properly or are always late, you get fired."
Hours of fitness, speed and gym work were intertwined with scrummaging and throwing drills, core roles the national coaches encouraged Harris to bone up on.
It's helped, too, that he's inherited a bit of the family pedigree, with his dad Quentin a take-no-prisoners Te Puke player who would feel shortchanged if he trudged off the field without blood - his or someone else's - staining his jersey. '
"Dad was a bit of a mongrel, whereas I think of myself more as a ball-playing hooker. I tried to get Dad back last year to play because it would have been fun alongside him, but he's had three back operations.
"We played the odd game, golden oldies or married vs singles, but he'd always make sure he was on the opposite side and try to take my head off."
Harris targeted his hooking rivals at the national trials and camps, tagging himself as underdog and willing himself to be better.
One challenger fractured his foot (although Harris swears he was nowhere close when it happened) and it helps that the team's fast-paced game plan suits his 1.82m, 106kg frame and a game modelled on Springbok Bismarck Du Plessis.
The winning legacy left by the under-20 side (New Zealand have won all four previous world titles) looms large and the fresh crop set off without any Super 15 stars. Harris isn't bothered.
"It's been a talking point but not amongst us. If we can become a better team, rather than relying on five or six individuals like other teams will be, then we'll unite on the field better and uphold the big legacy that's been left."